河口沼泽湿地转化为养虾塘对土壤胞外酶活性及CO_(2)和CH_(4)产生潜力的影响

Effects of conversion of estuarine marshes to shrimp ponds on soil extracellular enzymes and CO_(2)and CH_(4)production potentials

揭示河口沼泽湿地围垦为水产养殖塘对土壤胞外酶活性和含碳温室气体产生的影响,可为评估土地利用/覆盖变化对滨海蓝碳湿地生态系统碳循环的影响提供科学依据.以闽江河口为研究区,对芦苇(Phragmites australis)湿地、短叶茳芏(Cyperus malaccensis)湿地和互花米草(Spartina alterniflora)湿地土壤(0~30 cm)和由其围垦成的养虾塘沉积物(0~30 cm)进行配对采集.通过室内厌氧培养实验,测定沼泽湿地土壤及由其围垦成的养虾塘沉积物的土壤胞外酶活性和CO_(2)、CH_(4)产生潜力.与河口沼泽湿地0~30 cm深度土壤相比,养虾塘0~30 cm深度沉积物4种土壤胞外酶活性均值降低27.3%.河口沼泽湿地转化为养虾塘后含碳温室气体产生潜力发生显著变化,芦苇沼泽、短叶茳芏沼泽、互花米草沼泽围垦成养虾塘后CO_(2)产生潜力分别增加5.1%、38.5%、38.8%,CH_(4)产生潜力分别降低24.9%、11.1%、21.1%,有机碳厌氧矿化速率分别增加4.9%、38.6%、38.4%.土壤有机碳(SOC)含量是影响土壤/沉积物胞外酶活性的关键因素,土壤胞外酶活性和沉积物电导率分别是河口沼泽湿地土壤和围垦养虾塘沉积物有机碳厌氧矿化速率的主要控制因素.研究表明:河口沼泽湿地围垦成的养虾塘沉积物有机碳厌氧矿化速率较围垦前的沼泽湿地土壤显著增加,可能导致河口沼泽湿地土壤有机碳的损失,不利于“双碳”目标的实现及全球气候变暖的缓解.

In order to scientifically assess the impact of land use/cover changes on carbon cycle of coastal blue carbon wetland ecosystem,it is important to reveal the effect of conversion of estuarine marshes to aquaculture ponds on soil extracellular enzyme activity and greenhouse gases production.Soil samples(0~30cm)from the Phragmites australis marshes,Cyperus malatensis marshes and Spartina alterniflora marshes,and 0~30 cm sediment samples from the shrimp ponds reclaimed from the above marshes were collected in the Min River estuary.The soil/sediment extracellular enzyme activity,and CO_(2),CH_(4)production potentials were measured via anaerobic incubation experiment.Compared with the marshes,the average value of activity of 4 extracellular enzymes in the shrimp ponds decreased by 27.3%.The production potentials of carbon greenhouse gases significantly changed after estuarine marshes converting to shrimp ponds.The CO_(2)production potentials of the P.australis marshes,C.malaccensis marshes,S.altemiflora marshes increased by 5.1%,38.5%and 38.8%,respectively,and the CH_(4)production potentials reduced by 24.9%,11.1%and 21.1%,respectively,and the organic carbon anaerobic mineralization rates increased by 4.9%,38.6%and 38.4%,respectively.The SOC content was key factor affecting the soil/sediment extracellular enzyme activity.The extracellular enzyme activity and conductivity were main factors controlling organic carbon anaerobic mineralization rate of the marshes soils and shrimp ponds sediments,respectively.The study results show that conversion from marsh to shrimp ponds in the Min River estuary increase organic carbon anaerobic mineralization rate,which may cause more loss of soil organic carbon,and is unfavorable to reach carbon goal of peak and neutrality and to mitigate global climate warming.